The present invention relates to identification systems and, more particularly, to identification systems for use on material handling vehicles.
Material handling vehicles, such as man-up fork lift trucks, often have certain operating limitations by which vehicle speed and geometry (sometimes referred to as base leg opening or stance) are related. In order to ensure stable operation of a vehicle, especially in the course of performing unusual operations, such as those involved with turning corners or making sudden maneuvers, geometry and operating parameters must be compatible.
Thus, a particular geometry in which a person is transported by the vehicle carriage at a given height above ground would normally allow only selected speeds or a predetermined maximum speed of the vehicle. In other words, the man-up vehicle may become unstable if either the velocity exceeds the predetermined maximum speed or the height of the carriage and its load above ground exceeds the predetermined height for that velocity.
A maximum speed for a fork lift truck decreases as the height of its load increases, since the maximum speed limit changes as the relative position of movable parts within a machine.
Simply stated, the maximum speed limit is a function of the load height. Vehicle stability, therefore, is a function of its geometry, such as: base leg opening or stance, turning radius, and vehicle weight, with or without load.
For the same load height, a more stable vehicle will have a higher maximum speed than a less stable vehicle.
Although manufacturers of material handling vehicles are very careful to design them to be stable for most conceivable situations, unauthorized replacements and substitutions of components in the field often change the stability of the vehicle in ways unintended by the manufacturer.
Such a situation can typically arise when a control processor is exchanged. In such a circumstance, the computer program that operates the vehicle may not be suitable for the new configuration, and instability becomes more likely.
Until this invention, material handling vehicles have not been successfully able to detect and relate to new configurations and operating parameters. Thus, occasional unstable situations will likely occur.
As far as is known, no one has ever attempted to use solid state electronic memory to maintain geometric identification.
In a prior generation vehicle, for example, a cammed, coded rail was arranged such that, as a load was lifted, a switch detected a series of on and off signals. The control system then translated these signals into an ID number, and modified its performance accordingly.
A more recent approach has been to allow the vehicle to adjust its performance according to inputs received. This adaptive learning method is discussed in a pending U.S. patent application, Ser. No. 07/199,782, filed May 26, 1988, for "Lift Truck Control System," assigned to the present assignee and incorporated herein by reference.
It would be advantageous to provide a system that would adjust the vehicle for the installation of mismatched components, especially electronic components, which might produce instability.
It would also be advantageous to provide a failsafe method and system by which a vehicle could not be operated unless its specified configuration or geometry were used with an appropriately suitable processing routine.
It would be advantageous to provide a generic control system which can automatically tailor its performance to the specific machine in which it is installed. The benefits of such a system would be many, such as: (1) ease of installation, (2) ensured stability, (3) elimination of the need to configure switches or firmware for the specific vehicle, and (4) elimination of inadvertent and unauthorized installations of control systems that will produce an unsuitable or dangerous configuration.
Sophisticated material handling vehicles may be purchased with many operational features. Such options typically include, but are not necessarily limited to: improved hardware and/or software, sophisticated electric battery discharge tracking capabilities, or mechanisms by which the carriage descends at a variable rate of speed as a function of its relative position with the floor.
Any option that is included in a vehicle should be controlled by suitable software, which software should be able to determine the vehicle configuration.
It is customary practice to provide each manufactured vehicle with all the aforementioned options. Access to any one or more options requires proper authorization. Likewise, certain options cannot be enabled by certain users. In this manner, the vehicle is customized to customer specifications, utilizing authorized manufacturing techniques.
It would be advantageous, therefore, to monitor such options and limit operating characteristics of the vehicle in accordance with safe practices and procedure.